Optimal Frequency of Shock Wave Lithotripsy in Urolithiasis Treatment: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Purpose: The optimal frequency of shock wave lithotripsy in urolithiasis has not been well determined. Materials and Methods: A search of MEDLINE (R), Web of Science and the Cochrane Library was performed. All randomized controlled trials including articles and meeting abstracts that compared the effects of different frequencies (120, 90 and 60 shock waves per minute) of shock wave lithotripsy were included in analysis. The review process followed the guidelines of the Cochrane Collaboration. Results: Nine randomized controlled trials including 1,572 cases were identified. Overall success rates and success rates for large stones (greater than 10 mm) were significantly lower in the 120 vs 60 (p <0.001 and p = 0.002, respectively) and in the 120 vs 90 (p <0.001 and p = 0.02, respectively) shock waves per minute groups, but similar between the 90 and 60 shock waves per minute groups. Treatment duration was significantly shorter in the 120 vs 60, 120 vs 90 and 90 vs 60 shock waves per minute groups (all p <0.001). Success rates for small stones (less than 10 mm), complication rates and total shock waves had no significant differences among the 3 groups. Conclusions: Decreasing the frequency from 120 to 60 shock waves per minute increased overall success rates. While the treatment duration of 60 shock waves per minute was much greater, 90 shock waves per minute seemed to be optimal, especially for large stones. A frequency of 120 shock waves per minute might still be recommended for small stones.